Question: The scale on a map is 10cm : 6km. If two cities are 70cm apart on the map, what is the actual distance in km between the two cities?
Solution: The scale means that every 10cm on the map corresponds to an actual distance of 6km. A distance of 70cm on the map is the same as 7 $\cdot$ 10cm. The actual distance between the two cities is 7 $\cdot$ 6km, or 42km.